1. Field of the Invention
The present invention relates to a spin MOSFET and a reconfigurable logic circuit using the spin MOSFET.
2. Related Art
In recent years, devices having novel functions have been actively studied and developed. One example of such a device is a spin MOSFET having source and drain units formed with magnetic materials. The spin MOSFET is characterized in that the output properties can be controlled simply by reversing the spin moment of the magnetic material of at least one of the source and drain units. Taking advantage of this aspect, it is possible to form a spin MOSFET structure having a reconfigurable function and an amplifying function, or a reconfigurable logic circuit (see APL84 (2004) 2307, for example).
As a method for reversing the spin direction of a memory layer in an MRAM (Magnetic Random Access Memory), there has been a method for performing writing through spin injection (see U.S. Pat. No. 6,256,223, for example). It has been confirmed that the spin direction of a memory layer is reversed by applying a spin-polarized current into an MRAM through spin injection. To use this spin-injection writing method in a spin MOSFET, there has been a structure that has a ferromagnetic tunnel junction (hereinafter also referred to as MTJ (magnetic Tunnel Junction)) having a stacked structure formed with a ferromagnetic layer, an insulating layer, and a ferromagnetic layer in one of the source and drain regions (see JP-A 2008-66596 (KOKAI), for example). With the use of the structure disclosed in JP-A 2008-66596 (KOKAI), the MR ratio of the MTJ is added to the MR ratio achieved through the channel region. Accordingly, the structure has the advantages that the read output can be greatly increased, and a magnetization reversal can be performed through spin injection, since the MTJ is provided.
To realize the structure disclosed in JP-A 2008-66596 (KOKAI), however, it is necessary to prepare the source unit and the drain unit separately from each other. As a result, there is an increase in production costs.